Multiple large blasts have rocked Kenya’s Westgate Mall where a deadly hostage siege is in its third day.

Reporters on the scene Monday heard multiple blasts and a barrage of gunfire, with black and gray smoke visible.

Security forces have been trying to rescue an unknown number of hostages inside the mall held by terrorists who had already killed at least 68 people, army officials said.

The blasts come one day after soldiers stormed the upscale Nairobi shopping mall, rescuing most of the remaining hostages.

The FBI was investigating whether as many as five Somali-Americans were among the terrorists, Fox News reported, while FBI agents and Israeli commandos were said to have aided in the rescue mission.

“Most of the hostages have been released, and the Kenya Defense Forces has taken control of most parts of the building,” Kenyan military spokesman Col. Cyrus Oguna earlier told local television station KTN.

At least 10 hostages remained captive as dawn broke Monday in the Kenyan capital, the BBC reported. It wasn’t clear how many gunman were still inside.

Oguna added that “most probably,’’ some of the 10 to 15 terrorists — who specifically targeted non-Muslims — were killed after the soldiers stormed the Westgate Shopping Mall in a bid to end the bloody two-day standoff.

According to reports, a white woman was among the hostage- takers. When asked if the suspect was British national Samantha Lewthwaite, known as the “White Widow,” who is reputed to be a leading jihadi, Kenyan authorities said they were ruling nothing out, CNN reported.

Britain’s The Guardian newspaper reported that two Kenyan soldiers were killed when they came under heavy fire. Four other soldiers were wounded, according to a tweet from the KDF.

The State Department said no US citizens were killed, but the wife of an American working for the US Agency for International Development was slain. Five Americans were wounded.

The nephew of the country’s president, as well as the nephew’s wife, were among the dead.

The Associated Press released amateur video of the attack Monday, showing scared shoppers running and hiding in store aisles as the gunmen started blasting.

There were conflicting reports about the possible involvement of American citizens in the attack, in which more than 175 people were injured.

NBC said the FBI was investigating whether the terrorists included as many as five Americans, based on “a Twitter feed purporting to represent . . . al-Shabab,” a Somali terrorist group, which “listed specific names and home states of the Americans they said were on their side.”

CNN tweeted earlier that three Americans were among the thugs, quoting “sources” within al-Shabab, which is linked to al Qaeda and has claimed responsibility for the bloodbath.

But an Associated Press reporter based in Nairobi said the CNN report was based on a “fake Twitter account.”

There were reports that Israeli commandos and the FBI assisted the Kenyan army in its assault on the mall, which is at least partially owned by Israelis.

“The Israelis have just entered, and they are rescuing the hostages and the injured,” a Kenyan security source told Kenya’s Daily Nation newspaper.

The Israeli Foreign Ministry refused to confirm or deny its forces were involved, the newspaper said.

Earlier in the day, US Rep. Peter King (R-LI) said al-Shabab has recruited up to 50 people from Somali-American communities in the US for its operations.

The army’s rescue operation began shortly before sundown Sunday, with two helicopters circling to the mall and one skimming the roof.

A Kenyan soldier said that the terrorists were using a PKM belt-fed machine gun to defend their stronghold and that government forces were returning fire and conducting floor-to-floor sweeps as they closed in on the killers.

President Uhuru Kenyatta reiterated his government’s determination to continue fighting al-Shabab, vowing, “We shall not relent on the war on terror.”